Question

Let $A=\{9,10,11,12,13\}$ and $f:A\to N$ be defined by $f\left(n\right)=$ highest prime factor of $n$, then its range is

• A. $\left\{13\right\}$
• B. $\{3,5,11,13\}$
• C. $\{11,13\}$
• D. $\{2,3,5,11\}$

Answer 1

The correct option is B $\{3,5,11,13\}$

$A=\{9,10,11,12,13\}$
$f\left(A\right)=$ highest prime factor of A
$\therefore$ Highest prime factor of $9=3$
Highest prime factor of $10=5$
Highest prime factor of $11=11$
Highest prime factor of $12=3$
Highest prime factor of $13=13$
So range of $f$ is $\{3,5,11,13\}$